In CNC machining, thread insert is chosen over direct tapping for threaded holes to meet performance requirements in specific working conditions and overcome the limitations of direct tapping.

1. Enhanced Thread Strength for Soft/Low-Strength Materials

Direct tapping strength depends entirely on part material properties. Issues occur with soft materials (aluminum, plastic) or low-strength materials (cast iron, thin plate):

• Thread deformation/stripping in soft materials
• Insufficient load-bearing in low-strength materials

Solution: Thread inserts made of stainless steel/high-carbon steel transfer bolt forces to parent material, acting as a "high-strength protective layer".

2. Easier Thread Repair, Reducing Scrap Risk

Direct tapping repair challenges:

• Size increases may damage part structure
• Precision parts forbid specification changes

Advantage: Damaged inserts can be replaced by removing old insert, re-tapping, and inserting new one - restoring original size without scrapping parts.

3. Thread Size Conversion Flexibility

Direct tapping requires complete re-machining for specification changes. Thread inserts allow adjustments through base hole size and insert specifications.

4. Improved Corrosion/Wear Resistance

Direct tapping threads inherit parent material weaknesses (e.g., rust-prone steel). Inserts provide:

• Superior corrosion-resistant materials
• Smooth surfaces reducing friction/rust

5. Compatibility With Thin-Walled/Special Structures

Direct tapping issues:

• Tool radial force deforms thin walls
• Poor accuracy in deep/blind holes

Insert benefits: Minimal deformation during installation + customizable lengths for deep holes.